Workshop 2. Genome-scale RNAi Screening General description RNA interference (RNAi) is an extremely powerful technology for probing gene function. Functionally, RNAi derives its utility from the ability of small double-stranded RNAs (small interfering RNA or siRNAs) to specifically silence genes containing sequences identical to those in the small RNAs. Since RNAi can be used to silence either specific pathogen genes or to silence specific genes in the host cell that might be involved in the pathogenic process, it represents an extremely valuable approach for studying host-pathogen interactions, characterizing individual microbial virulence factors, and identifying host genes involved in pathogen replication and virulence. This workshop will describe RNAi technology and genome-scale RNAi screening capabilities available at the ICCB-L screening facility at Harvard Medical School.